112 lines
2.3 KiB
Go
112 lines
2.3 KiB
Go
// Package newsletter manages email subscriber storage as a flat JSON file.
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package newsletter
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import (
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"encoding/json"
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"errors"
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"os"
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"strings"
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"sync"
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"time"
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)
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// Subscriber holds a single email subscription.
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type Subscriber struct {
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Email string `json:"email"`
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CreatedAt time.Time `json:"created_at"`
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}
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// Store manages subscribers persisted to a JSON file.
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type Store struct {
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mu sync.RWMutex
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path string
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}
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// NewStore returns a Store backed by path, creating the file if needed.
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func NewStore(path string) (*Store, error) {
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s := &Store{path: path}
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// Create empty file if it doesn't exist
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if _, err := os.Stat(path); os.IsNotExist(err) {
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if err := s.save(nil); err != nil {
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return nil, err
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}
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}
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return s, nil
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}
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// All returns all current subscribers.
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func (s *Store) All() ([]Subscriber, error) {
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s.mu.RLock()
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defer s.mu.RUnlock()
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return s.load()
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}
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// Add adds an email if it isn't already subscribed. Returns false if duplicate.
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func (s *Store) Add(email string) (bool, error) {
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email = strings.ToLower(strings.TrimSpace(email))
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if email == "" {
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return false, errors.New("email is required")
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}
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s.mu.Lock()
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defer s.mu.Unlock()
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subs, err := s.load()
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if err != nil {
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return false, err
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}
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for _, sub := range subs {
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if sub.Email == email {
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return false, nil // already subscribed
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}
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}
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subs = append(subs, Subscriber{Email: email, CreatedAt: time.Now().UTC()})
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return true, s.save(subs)
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}
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// Remove unsubscribes an email address.
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func (s *Store) Remove(email string) error {
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email = strings.ToLower(strings.TrimSpace(email))
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s.mu.Lock()
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defer s.mu.Unlock()
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subs, err := s.load()
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if err != nil {
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return err
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}
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filtered := subs[:0]
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for _, sub := range subs {
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if sub.Email != email {
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filtered = append(filtered, sub)
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}
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}
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return s.save(filtered)
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}
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func (s *Store) load() ([]Subscriber, error) {
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raw, err := os.ReadFile(s.path)
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if err != nil {
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return nil, err
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}
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if len(raw) == 0 {
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return nil, nil
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}
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var subs []Subscriber
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if err := json.Unmarshal(raw, &subs); err != nil {
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return nil, err
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}
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return subs, nil
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}
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func (s *Store) save(subs []Subscriber) error {
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if subs == nil {
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subs = []Subscriber{}
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}
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raw, err := json.MarshalIndent(subs, "", " ")
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if err != nil {
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return err
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}
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return os.WriteFile(s.path, raw, 0600)
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}
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